Field of the Invention
The present invention relates to an anti-foam chamber for screw compressor oil separators. Positive displacement rotary screw compressors used in refrigeration systems are normally provided with lubricating oil which is directly injected into the compression volume in order to seal the rotor clearance. This injected oil, along with the refrigerant gas, is pumped into a multi-stage oil separator to remove the injected oil before the gaseous refrigerant enters the refrigerant condenser.
Refrigerant screw compressors, as described above, have been developed which are designed to cool this circulating lubricating oil by direct injection of the primary refrigerant into the compression volume. This injected refrigerant liquid mixes with the injected lubricating oil.
In the primary section of the oil separator, this mixture creates a foaming condition and a false lubricating oil level, resulting in an inaccurate indication of the true operating lubricating oil level.
Due to the foaming action, it is possible to lose control of the oil level and the compressor may fail because of insufficient lubrication, even though a low oil pressure safety control is in the circuit.
The foaming action in the separator also creates an abnormally high level of lubricating oil and cavitation of the oil pump could result because the decreased density of the foaming mixture lowers the net positive suction head on the oil pump suction connection even though a higher level of mixture may be indicated.
This condition could cause a problem for operating engineers due to the actual loss of a visible true oil level caused by the foaming action which may force the surface of the mixture above the view ports supplied to provide a macroscopic indication of the operating oil level.